The Effect of Four-Lane to Three-Lane Conversion on the Number of Crashes and Crash Rates in Iowa Roads, June 2005

We analyze crash data collected by the Iowa Department of Transportation using Bayesian methods. The data set includes monthly crash numbers, estimated monthly traffic volumes, site length and other information collected at 30 paired sites in Iowa over more than 20 years during which an intervention experiment was set up. The intervention consisted in transforming 15 undivided road segments from four-lane to three lanes, while an additional 15 segments, thought to be comparable in terms of traffic safety-related characteristics were not converted. The main objective of this work is to find out whether the intervention reduces the number of crashes and the crash rates at the treated sites. We fitted a hierarchical Poisson regression model with a change-point to the number of monthly crashes per mile at each of the sites. Explanatory variables in the model included estimated monthly traffic volume, time, an indicator for intervention reflecting whether the site was a “treatment” or a “control” site, and various interactions. We accounted for seasonal effects in the number of crashes at a site by including smooth trigonometric functions with three different periods to reflect the four seasons of the year. A change-point at the month and year in which the intervention was completed for treated sites was also included. The number of crashes at a site can be thought to follow a Poisson distribution. To estimate the association between crashes and the explanatory variables, we used a log link function and added a random effect to account for overdispersion and for autocorrelation among observations obtained at the same site. We used proper but non-informative priors for all parameters in the model, and carried out all calculations using Markov chain Monte Carlo methods implemented in WinBUGS. We evaluated the effect of the four to three-lane conversion by comparing the expected number of crashes per year per mile during the years preceding the conversion and following the conversion for treatment and control sites. We estimated this difference using the observed traffic volumes at each site and also on a per 100,000,000 vehicles. We also conducted a prospective analysis to forecast the expected number of crashes per mile at each site in the study one year, three years and five years following the four to three-lane conversion. Posterior predictive distributions of the number of crashes, the crash rate and the percent reduction in crashes per mile were obtained for each site for the months of January and June one, three and five years after completion of the intervention. The model appears to fit the data well. We found that in most sites, the intervention was effective and reduced the number of crashes. Overall, and for the observed traffic volumes, the reduction in the expected number of crashes per year and mile at converted sites was 32.3% (31.4% to 33.5% with 95% probability) while at the control sites, the reduction was estimated to be 7.1% (5.7% to 8.2% with 95% probability). When the reduction in the expected number of crashes per year, mile and 100,000,000 AADT was computed, the estimates were 44.3% (43.9% to 44.6%) and 25.5% (24.6% to 26.0%) for converted and control sites, respectively. In both cases, the difference in the percent reduction in the expected number of crashes during the years following the conversion was significantly larger at converted sites than at control sites, even though the number of crashes appears to decline over time at all sites. Results indicate that the reduction in the expected number of sites per mile has a steeper negative slope at converted than at control sites. Consistent with this, the forecasted reduction in the number of crashes per year and mile during the years after completion of the conversion at converted sites is more pronounced than at control sites. Seasonal effects on the number of crashes have been well-documented. In this dataset, we found that, as expected, the expected number of monthly crashes per mile tends to be higher during winter months than during the rest of the year. Perhaps more interestingly, we found that there is an interaction between the four to three-lane conversion and season; the reduction in the number of crashes appears to be more pronounced during months, when the weather is nice than during other times of the year, even though a reduction was estimated for the entire year. Thus, it appears that the four to three-lane conversion, while effective year-round, is particularly effective in reducing the expected number of crashes in nice weather.

Experimental design on the simplex

Optimum experimental designs depend on the design criterion, the model andthe design region. The talk will consider the design of experiments for regressionmodels in which there is a single response with the explanatory variables lying ina simplex. One example is experiments on various compositions of glass such asthose considered by Martin, Bursnall, and Stillman (2001).Because of the highly symmetric nature of the simplex, the class of models thatare of interest, typically Scheff´e polynomials (Scheff´e 1958) are rather differentfrom those of standard regression analysis. The optimum designs are also ratherdifferent, inheriting a high degree of symmetry from the models.In the talk I will hope to discuss a variety of modes for such experiments. ThenI will discuss constrained mixture experiments, when not all the simplex is availablefor experimentation. Other important aspects include mixture experimentswith extra non-mixture factors and the blocking of mixture experiments.Much of the material is in Chapter 16 of Atkinson, Donev, and Tobias (2007).If time and my research allows, I would hope to finish with a few comments ondesign when the responses, rather than the explanatory variables, lie in a simplex.ReferencesAtkinson, A. C., A. N. Donev, and R. D. Tobias (2007). Optimum ExperimentalDesigns, with SAS. Oxford: Oxford University Press.Martin, R. J., M. C. Bursnall, and E. C. Stillman (2001). Further results onoptimal and efficient designs for constrained mixture experiments. In A. C.Atkinson, B. Bogacka, and A. Zhigljavsky (Eds.), Optimal Design 2000,pp. 225–239. Dordrecht: Kluwer.Scheff´e, H. (1958). Experiments with mixtures. Journal of the Royal StatisticalSociety, Ser. B 20, 344–360.1

Factors associated with involuntary hospital admissions in technology-dependent children

Abstract OBJECTIVE To identify the factors associated with involuntary hospital admissions of technology-dependent children, in the municipality of Ribeirão Preto, São Paulo State, Brazil. METHOD A cross-sectional study, with a quantitative approach. After an active search, 124 children who qualified under the inclusion criteria, that is to say, children from birth to age 12, were identified. Data was collected in home visits to mothers or the people responsible for the children, through the application of a questionnaire. Analysis of the data followed the assumptions of the Generalized Linear Models technique. RESULTS 102 technology-dependent children aged between 6 months and 12 years participated in the study, of whom 57% were male. The average number of involuntary hospital admissions in the previous year among the children studied was 0.71 (±1.29). In the final model the following variables were significantly associated with the outcome: age (OR=0.991; CI95%=0.985-0.997), and the number of devices (OR=0.387; CI95%=0.219-0.684), which were characterized as factors of protection and quantity of medications (OR=1.532; CI95%=1.297-1.810), representing a risk factor for involuntary hospital admissions in technology-dependent children. CONCLUSION The results constitute input data for consideration of the process of care for technology-dependent children by supplying an explanatory model for involuntary hospital admissions for this client group.

The illusion of control, the structures of prizes and the demand for football pools in Spain

Using data for all the fixtures for the seasons from 1972-73 to 2002-03, we estimate a dynamic model of demand for football pools in Spain paying attention to whether their main economic explanatory variable is the effective price of a ticket or the jackpot. Additionally, we evaluate the importance of the composition of the list of games in terms of whether First Division matches are included or not. Results show that the jackpot model is preferred to the effective price model, having important implications in terms of how the structure of the game should be changed in order to increase demand.

Launching prices for new pharmaceuticals in heavily regulated and subsidized markets

This paper provides empirical evidence on the explanatory factorsaffecting introductory prices of new pharmaceuticals in a heavilyregulated and highly subsidized market. We collect a data setconsisting of all new chemical entities launched in Spain between1997 and 2005, and model launching prices. We found that, unlike inthe US and Sweden, therapeutically "innovative" products are notoverpriced relative to "imitative" ones. Price setting is mainly used asa mechanism to adjust for inflation independently of the degree ofinnovation. The drugs that enter through the centralized EMAapproval procedure are overpriced, which may be a consequence ofmarket globalization and international price setting.

Fuzzy coding in constrained ordinations

Canonical correspondence analysis and redundancy analysis are two methods of constrained ordination regularly used in the analysis of ecological data when several response variables (for example, species abundances) are related linearly to several explanatory variables (for example, environmental variables, spatial positions of samples). In this report I demonstrate the advantages of the fuzzy coding of explanatory variables: first, nonlinear relationships can be diagnosed; second, more variance in the responses can be explained; and third, in the presence of categorical explanatory variables (for example, years, regions) the interpretation of the resulting triplot ordination is unified because all explanatory variables are measured at a categorical level.

Un regard sur la politique forestière suisse (essai)

In the form of an essay, the author proposes a review of the reasons behind the recent changes in forestry policy. He identifies two explanatory elements and goes into these in more detail: the loss in cohesion in sectorial forestry logic since the 1980s, and the internal division which has arisen on account of the failure to put through the partial revision of the Federal Forestry Law. Firstly, it is clear that forestry practice continues to function on a sectorial basis, even though the management of resources increasingly extends between sectors. Accordingly, he also sees forestry management as being restricted by exterior influences. Secondly, the dichotomy between production and protection weakens the forestry community. The author hopes forestry will be able to overcome these problems and thus become (once more) an influential political protagonist.

Strengthening the Reporting of Observational Studies in Epidemiology (STROBE): explanation and elaboration.

Much medical research is observational. The reporting of observational studies is often of insufficient quality. Poor reporting hampers the assessment of the strengths and weaknesses of a study and the generalisability of its results. Taking into account empirical evidence and theoretical considerations, a group of methodologists, researchers, and editors developed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) recommendations to improve the quality of reporting of observational studies. The STROBE Statement consists of a checklist of 22 items, which relate to the title, abstract, introduction, methods, results and discussion sections of articles. Eighteen items are common to cohort studies, case-control studies and cross-sectional studies and four are specific to each of the three study designs. The STROBE Statement provides guidance to authors about how to improve the reporting of observational studies and facilitates critical appraisal and interpretation of studies by reviewers, journal editors and readers. This explanatory and elaboration document is intended to enhance the use, understanding, and dissemination of the STROBE Statement. The meaning and rationale for each checklist item are presented. For each item, one or several published examples and, where possible, references to relevant empirical studies and methodological literature are provided. Examples of useful flow diagrams are also included. The STROBE Statement, this document, and the associated Web site (http://www.strobe-statement.org/) should be helpful resources to improve reporting of observational research.

Perfil dos Turistas que Visitam a Ilha de São Vicente

O presente trabalho tem por objectivo definir o perfil do turista que visitou a ilha de São Vicente e avaliar o grau de satisfação do turista enquanto consumidor de diferentes bens e serviços, nos meses de Maio e Junho do decorrente ano. Para se fazer uma abordagem qualitativa falou-se da problemática do mercado turístico - procura e oferta turística – e a importância da segmentação desse sistema turístico juntamente com algumas teorias do comportamento do consumidor. Por sua vez, para o estudo do perfil e satisfação dos turistas utilizou-se uma abordagem quantitativa, através da aplicação de questionários no Aeroporto Internacional Cesária Évora e entrevistas aos estabelecimentos hoteleiros, 150 e 7 respectivamente. Após a análise explicativa, com base na bibliografia seleccionada, nas entrevistas e questionários realizados, os resultados da pesquisa indicam que estudar o perfil e a satisfação dos turistas permite fazer um levantamento de diversas variáveis importantes como, por exemplo, a nacionalidade do turista, a principal razão e objectivo da viagem e o que gostaram, ou desejavam ver no destino. E assim, entender-se o perfil do visitante e propor-se estratégias, que contribuam para um planeamento sustentável do desenvolvimento turístico na região pretendida. A complexidade do processo de decisão do turista por um ou outro destino é que verdadeiramente motiva esta pesquisa. The objective of the following work is to define the profile of a tourist that visited São Vicente, and evaluate the levels of satisfaction of the tourist as a consumer of different items and services, on May and June of the current year. For a quality methodological approach, the problematic of the touristic industry (demand and touristic offer) – the essential of subdivision of these touristic systems alongside with the principles of the consumer behavior were discussed. In continuity, to define the profile and satisfaction of the tourists, a quantity approach was also used, through the application of questionnaires at the International Airport Cesária Évora and interviews throughout hotel establishments, 150 and 7 respectively. After an explanatory analyses, based on a selected bibliography, the applied interviews and questionnaires, the outcome of this research shows that by studying the profile and the satisfaction of the tourists allows to have variable important results, for example, the tourist´s nationality, the main reason and objective of the trip and what they enjoyed or would like to see on their destination. Thus, understanding the visitor´s profile and suggesting strategies, that contributes for a sustainable planning of a touristic development on the intended region. The process complexity of the decision making of the tourist for one destination is truly the main motivation for this research.

Technical inefficiency and public capital in US States: A stochastic frontier approach

This paper estimates a translog stochastic frontier production function in the analysis of all 48 contiguous U.S. states in the period 1970-1983, to attempt to measure and explain changes in technical efficiency. The model allows technical inefficiency to vary over time, and inefficiency effects to be a function of a set of explanatory variables in which the level and composition of public capital plays an important role. Results indicated that U.S. state inefficiency levels were significantly and positively correlated with the ratio of public capital to private capital. The proportion of public capital devoted to highways is negatively correlated with technical inefficiency, suggesting that not only the level but also the composition of public capital influenced state efficiency.

A Implementação de um Sistema de Controlo Interno na Área de Recursos Humanos: O Caso da Universidade de Cabo Verde – Uni-CV-Reitoria da praia

Os recentes acontecimentos verificados em algumas organizações nacionais e estrangeiras, remetem um fraco grau de transparência no que refere a fiabilidade no desempenho e responsabilidades dos seus colaboradores. Este trabalho tem como objectivo propor a implementação de um sistema de controlo interno na Uni-CV, Reitoria da Praia, na área de recursos humanos. Para chegar ao resultado esperado foi realizada uma pesquisa explicativa, com abordagem qualitativa e quantitativa desenvolvendo-se através de fontes já existentes, com a análise dos dados resultantes do questionário aplicado. A fundamentação teórica abordou os aspectos mais importantes do controlo interno e recursos humanos. O caso prático foi realizado, pelas suas características, se considera de grande relevância não só para com a organização em si, mas também, para a administração pública cabo-verdiana, de forma que, quando implementadas, contribuirão para o bom desempenho das instituições. A análise dos dados obtidos com a aplicação do questionário, ao Director Administrativo e Financeiro da Reitoria da Praia e a observação participante dos procedimentos na área de recursos humanos possibilitaram verificar a necessidade de implementação de um sistema de controlo interno adequado e rigoroso, e um internal controller, que será o responsável pelo controlo das rotinas na área dos RH (Auditor interno) e modelar o tipo de controlo interno a ser aplicado na referida área.

Allowing for heterogeneity in the decomposition of measures of inequality in health

This paper shows how recently developed regression-based methods for the decomposition ofhealth inequality can be extended to incorporate heterogeneity in the responses of health to the explanatory variables. We illustrate our method with an application to the GHQ measure of psychological well-being taken from the British Household Panel Survey. The results suggest that there is an important degree of heterogeneity in the association of health to explanatory variables across birth cohorts and genders which, in turn, accounts for a substantial percentage of the inequality in observed health.

Lidar com a doença mental : a pluralidade de sistemas de cuidados e de itinerários terapêuticos : análise comparativa de dois estudos efectuados junto de duas populações residentes em Portugal

Several studies point to the plurality of care systems to deal with illness. They can be organized into professional, popular and alternative systems (the latter includes the complementary and the traditional ones). What the particular setup is in each cultural system is the core question of both the empirical studies we report. The purpose of this article is to understand how lay people deal with mental illness, examining the therapeutic itineraries that are constructed between plural care systems, featuring in particular the use of traditional medicine. The analysis of the two studies (one carried out in the north region and the other in Lisbon) allowed us to interpret these practices and discuss the social and cultural factors that determine and explain the settings that were found. Both researches fit into a qualitative methodology. In-depth, semi-structured interviews were performed and were analyzed using discourse analysis to describe and interpret data. The results point to a plurality of therapeutic itineraries, built around public and private speeches, where the explanatory systems underlying the use of official medicine and/or traditional practices found plural meanings. People may use these systems in several forms, using one or combining more than one, simultaneously or sequentially, depending on the context and on the needs they feel to face both illness and mental suffering. It is in between the space of the impotence and ‘incompetence’ of the ‘wise’ medicine that other therapeutic systems develop. It is important to understand those systems because of their achievements and their heuristic power to explain society and culture.

Finance versus costs for teaching hospitals in Spain

In this paper we analyse the observed systematic differences incosts for teaching hospitals (THhenceforth) in Spain. Concernhas been voiced regarding the existence of a bias in thefinancing of TH s has been raised once prospective budgets arein the arena for hospital finance, and claims for adjusting totake into account the legitimate extra costs of teaching onhospital expenditure are well grounded. We focus on theestimation of the impact of teaching status on average cost. Weused a version of a multiproduct hospital cost function takinginto account some relevant factors from which to derive theobserved differences. We assume that the relationship betweenthe explanatory and the dependent variables follows a flexibleform for each of the explanatory variables. We also model theunderlying covariance structure of the data. We assumed twoqualitatively different sources of variation: random effects andserial correlation. Random variation refers to both general levelvariation (through the random intercept) and the variationspecifically related to teaching status. We postulate that theimpact of the random effects is predominant over the impact ofthe serial correlation effects. The model is estimated byrestricted maximum likelihood. Our results show that costs are 9%higher (15% in the case of median costs) in teaching than innon-teaching hospitals. That is, teaching status legitimatelyexplains no more than half of the observed difference in actualcosts. The impact on costs of the teaching factor depends on thenumber of residents, with an increase of 51.11% per resident forhospitals with fewer than 204 residents (third quartile of thenumber of residents) and 41.84% for hospitals with more than 204residents. In addition, the estimated dispersion is higher amongteaching hospitals. As a result, due to the considerable observedheterogeneity, results should be interpreted with caution. From apolicy making point of view, we conclude that since a higherrelative burden for medical training is under public hospitalcommand, an explicit adjustment to the extra costs that theteaching factor imposes on hospital finance is needed, beforehospital competition for inpatient services takes place.

Association of socioeconomic position with health behaviors and mortality

CONTEXT: Previous studies may have underestimated the contribution of health behaviors to social inequalities in mortality because health behaviors were assessed only at the baseline of the study. OBJECTIVE: To examine the role of health behaviors in the association between socioeconomic position and mortality and compare whether their contribution differs when assessed at only 1 point in time with that assessed longitudinally through the follow-up period. DESIGN, SETTING, AND PARTICIPANTS: Established in 1985, the British Whitehall II longitudinal cohort study includes 10 308 civil servants, aged 35 to 55 years, living in London, England. Analyses are based on 9590 men and women followed up for mortality until April 30, 2009. Socioeconomic position was derived from civil service employment grade (high, intermediate, and low) at baseline. Smoking, alcohol consumption, diet, and physical activity were assessed 4 times during the follow-up period. MAIN OUTCOME MEASURES: All-cause and cause-specific mortality. RESULTS: A total of 654 participants died during the follow-up period. In the analyses adjusted for sex and year of birth, those with the lowest socioeconomic position had 1.60 times higher risk of death from all causes than those with the highest socioeconomic position (a rate difference of 1.94/1000 person-years). This association was attenuated by 42% (95% confidence interval [CI], 21%-94%) when health behaviors assessed at baseline were entered into the model and by 72% (95% CI, 42%-154%) when they were entered as time-dependent covariates. The corresponding attenuations were 29% (95% CI, 11%-54%) and 45% (95% CI, 24%-79%) for cardiovascular mortality and 61% (95% CI, 16%-425%) and 94% (95% CI, 35%-595%) for noncancer and noncardiovascular mortality. The difference between the baseline only and repeated assessments of health behaviors was mostly due to an increased explanatory power of diet (from 7% to 17% for all-cause mortality, respectively), physical activity (from 5% to 21% for all-cause mortality), and alcohol consumption (from 3% to 12% for all-cause mortality). The role of smoking, the strongest mediator in these analyses, did not change when using baseline or repeat assessments (from 32% to 35% for all-cause mortality). CONCLUSION: In a civil service population in London, England, there was an association between socioeconomic position and mortality that was substantially accounted for by adjustment for health behaviors, particularly when the behaviors were assessed repeatedly.